Question on file format - large JPG files needed

[Moonstruck]

I will be sending a few astro pictures to a local magazine for publication, and they require my photos be in JPG format, and a minimum of 300dpi and from 3-5MB. They do not accept tiff, or any other type of files. Is there a way that I can save the files in startools as JPGs this size, at the required resolution? If so, how would I do that?

[Mike in Rancho]

Hi John!

First, congrats!

Second, well hmmm ( ), I'm not sure dpi has any meaning at all, unless they can tell you ahead of time what dimension (in inches) they intend to reproduce/print your images at. Then, you could fiddle with things to make it conform, I guess.

I take it they want to print at 300 dpi, and further presume each "dot" will be a digital image pixel. Divide your picture's resolution by 300 to figure out what the spatial size in inches would be. Or, if they can give you a dimension in inches that the photos will print at, you can multiply that by 300 to get a top resolution in dots/pixels. I don't know what their max photo size is, but it seems to me an 8.5 x 11 piece of paper would be 2550 x 3300 dots/pixels.

Are you going to get maybe the top half of a page, a whole page sideways in landscape, or maybe a...centerfold?

Anyway then you could resample (down, I presume, but am unsure) your images to fit that size. I would use Gimp because that's what I have, and it seems to have pretty good scaling plus fully variable compression on jpg conversion. Personally I think I would want 100% on the jpg quality. Other image programs may be good at this too, PS perhaps.

One thing you could do is open your image in Gimp and simply export to jpg, 100% quality, without resampling, and see if it is bigger than 5MB, since that's a hard limit it seems. To get some idea of where your particular images might fall and put some constraints on working things out with them.

Any of that make sense? Maybe I'm off my rocker.

If you find any more info out, let us know!

[Moonstruck]

Hey Mike! Yes, I got lucky and a magazine agreed to publish my article on astrophotography. I have had a few astronomy/astrophotography articles in local newspapers but this is the first time for a magazine... I'm very excited! My pictures have been getting a little better lately, and I have been using my Celestron C8 Edge with reducer and asi 294 for galaxies. It makes a world of difference- galaxy images are bigger and clearer now than with my smaller Esprit 100mm scope.

Anyway, the editor contacted me and told me their photo requirements of 300dpi and 3-5MB, and that they can only use JPG files. I have no idea what sizes the pictures will actually be within the article, what orientation in the article will appear, or if they will publish all of them that I submitted. Yes a centerfold would be nice . I think their dpi and size requirements are just their general guidelines. I tried to give them jpgs of about 300-500kb but he was firm on their size requirements, thus my post...

I see that Startools allows files to be saved as a jpg, so I tried it with one and it was only around 800kb. Thus far I have been generating Tiff files in startools and converting them to jpg afterwards in GIMP, but after conversion of a big (say, 20MB or over) tiff file, the JPG is still under 1MB- they are getting very compressed in GIMP's conversion process. I see that GIMP has a "picture quality" slider when converting, and even with that at the highest quality I still can't get close to a 3MB file.

So... I put a post on CN asking for help, and heard about a program called "Topaz gigapixel AI," which increases file size and resolution with artificial intelligence. I downloaded it and it works great. My files are now JPGs at or close to 3-5MB, and they are better (sharper, clearer) photos. BUT.. this comes at a price. With "artificial intelligence," it inserts pixels to fill in the blanks. So the resulting photo is not really true to life. It looks the same as the smaller file versions but is more detailed due to the added pixels. So, is that a true representation of the object? That is a grey area... I wish there was some way to make files bigger without inserting pixels. But if you look at the concept of astrophotography in general, anything is up to interpretation and there are a lot of things that are not (or may not be) true to life, including color, intensity, etc. I made sure to have the program change the photo as little as possible as there are options for blur reduction, etc and tried to keep it as original as possible. It looked like this Topaz program was my only option to get the files big enough, so I went for it since my submission deadline was this week. I let the editor know what I was using in case he has any concerns.

Anyway, that's my story! If you haven't already, you should consider sending in some of your pictures to a newspaper or magazine. It's a great feeling of satisfaction when they are published. I have been contacted by several people wanting more information on amateur astronomy, and it feels good to be able to help them out.

[Mike in Rancho]

Hi John,

Well, it seem the chickens already left the roost, or sailed their ship, or whatever...

But I'm still not following the so-called requirements. Maybe somebody who knows photographic printing can chime in, as it really doesn't make sense.

Too bad on the Topaz thing. I don't quite understand what you mean by making your images "bigger," and certainly not "better." Plenty of discussion around here on stuff like that, I'm sure.

What was the resolution of your final tiff files right out of ST? Granted, too much binning will result in smaller dimensions and an accordingly smaller jpg. Also, the less going on in an image (small galaxy, compressed range on the background) also leads to smaller files.

For my Gimp conversions to jpg of ST images, for say Astrobin at 100% quality, I also have options changed (I think) in the advance options - no smoothing, and with progressive checked off the subsampling is on best quality. Smoothing is turned off. Actually I think the final file size will be even bigger if you turn progressive completely off.

Anywho, a quick review of some of my more recent "big" jpgs showed them to be kind of in the ballpark. M78 at 2150x1450 is about 3MB; Leo Triplet at 4400x2900 is 4.4MB; M81 at 2200x1400 was only 1.7MB; but M31 at 2200x1400 was over 3MB.

I still think they're being unnecessarily troublesome about "dpi" though.

Best thing, if you were going to say it was StarTools processed and not molested by Topaz afterwards, would probably be a process though while maintain a bit more resolution, then 100% jpg conversion in gimp with some extra changes in the advanced window.

I hope they look good when you see them in print though!

[dx_ron]

I use IrfanView (free) for file re-sizing and conversion to png and jpg. I particularly like its feature for jpg where you can specify a target file size (to meet posting guidelines here and at CN).

I just pulled up one of my ST tiffs. It is 2766x1847, so it would be 300dpi at about 9" wide. I saved as jpg with max quality and the size constraint turned off - it came out as 2.8MB, so pretty close to meeting your limits.

[decay]

I use IrfanView (free) for file re-sizing and conversion to png and jpg.

+1
I can recommand that as well. I have been using this tool for years. It's lightwight, powerful and easy to use (but Windows only).